This invention relates generally to lubricating agents for processing fibers and a method of processing fiber filaments by said lubricating agents and more particularly to a novel type of lubricating agents for processing fibers which can both produce excellent lubricity and reduce the rate of tar generation and a method of processing thermoplastic synthetic fiber filaments by using such lubricating agents.
Fabrics are made of many kinds of thermoplastic synthetic fibers such as polyester, polyamide, polypropylene and polyacrylnitrile or cellulose-type fibers such as rayon, cupra and acetates as well as natural fibers. Many processes are involved in the fabrication such as weaving, drawing, false twisting, twisting and pasting although some of these processes may be combined into a single process. Various kinds of lubricating agents are used in these processes.
It has been well known that these lubricating agents must be able to produce excellent lubricity and to reduce the rate of tar generating. For this reason, use has been made of not only mineral oils and aliphatic esters but also many kinds of lubricating agents having as main constituents, for example, polyoxyalkylene ethers (for example, U.S. Pat. No. 3,338,830), esters of polyoxyalkylene ether and aliphatic acid, formals of polyoxyalkylene alkyl ether, esters of polyoxyalkylene bisphenol and aliphatic acid, orthosilicate ester and silicone alkylene oxide copolymer. Although they all have certain advantages, however, each of these lubricating agents for processing fibers is unsatisfactory in view of the aforementioned requirements. Mineral oils and aliphatic esters, for example, do not inhibit the generation of tar. Polyoxyalkylene ethers and the aforementioned esters of bisphenol and aliphatic acid are not satisfactory in view of the lubricity requirement. Esters of polyoxyalkylene ether and aliphatic acid and aforementioned formals tend to cause swelling in rubber-like substances. As for formals, furthermore, their yields by synthesis are inferior and there is also the problem of removing the formal-generating reagent. Orthosilicate esters have the disadvantage that hydrolysis can take place easily inside an aqueous solution. As for silicone alkylene oxide copolymer, generation of tar is not inhibited sufficiently at the time of heating so that a large amount of varnish-like tar is produced from polydimethyl siloxane.
It has thus been desirable to provide an improved lubricating agent for processing fibers which can reduce these shortcomings of the conventional lubricating agents. In order to improve production efficiency, on the other hand, attempts have also been made to increase the processing speed. Nowadays, high quality products are being introduced and fiber filaments are made smaller (lower denier) while there remain tendencies that running filaments break, burrs appear on the filaments and heaters become covered with tar. For this reason, it is not a matter of mere desire to make improvements on the conventional lubricating agents. There is a strong demand for new lubricating agents for processing fibers which can not only satisfy the requirements regarding yarn lubricity and generation of tar but also overcome the difficulties mentioned above.